为什么在用sinon.js插入猫鼬时会收到“ TypeError：无法读取未定义的属性'restore'的信息”

我正在尝试用Sinon.js进行存根和模拟猫鼬，但我得到了错误：TypeError: Cannot read property 'restore' of undefined。我曾尝试过Google搜索和SO搜索，但都没有运气。有人可以告诉我我是否正确地处理了这个问题，如果是，我正在做错什么，会引发此错误。如果我要解决所有这些错误，那么我将向正确的方向表示感谢

这是我的模型/架构：

var Mongoose = require("mongoose");
var Schema = Mongoose.Schema;

exports = module.exports = function (host, database, port) {

    var mySchema = new Schema({
        name: {
            type: String,
            required: true,
            unique: true
        },
        addresses: {
            type: Array,
            required: false
        }
    }, {
        strict: true
    });
    mySchema.path('name').index({
        unique: true
    });

    var db = Mongoose.createConnection(host, database);
    var model = db.model('people', mySchema);
    var getAllPeople = function (callback) {

        var error = null,
            data = null;


        return model.find(function (err, people) {
            if (!err) {
                data = people;
            } else {
                error = err;
            }
            callback(error, people);
        });
    };

    return {
        Model: model,
        getAllPeople: getAllPeople

    };

}

这是我使用Mocha＆chai进行测试的规范：

var expect = require("chai").expect;
var sinon = require("sinon");
var PeopleProvider = require("../models/mySchema.js")("localhost", "test_db");
describe("Unit tests with sinon", function () {

    it("Test: stubbing find for getAllPeople", function (done) {

        var stub = sinon.stub(PeopleProvider.Model.prototype, 'find', function () {
            return [{
                name: "John",
                addresses: ["abc", "123", "xyz"]
            }, {
                name: "Jane",
                addresses: ["123 fake st", "somewhereville"]
            }, {
                name: "Joe",
                addresses: ["someplace", "overthere", "here"]
            }];
        }); 

        results = PeopleProvider.getAllPeople(function (error, data) {


            expect(data instanceof Array).to.equal(true);
            expect(data.length).to.equal(3);
            expect(data[0].name).to.equal("John");
            expect(data[0].addresses.length).to.equal(3);
            expect(data[0].addresses[0]).to.equal("abc");

            expect(data[1].name).to.equal("Jane");
            expect(data[1].addresses.length).to.equal(2);
            expect(data[1].addresses[0]).to.equal("somewhereville");

            expect(data[2].name).to.equal("Joe");
            expect(data[2].addresses.length).to.equal(3);
            expect(data[2].addresses[0]).to.equal("someplace");

            done();
        });

    });
});

这是我的堆栈错误：

  1) Unit tests with sinon Test: stubbing find for getAllPeople:
     TypeError: Cannot read property 'restore' of undefined
      at Object.wrapMethod (C:\~censored~\node_modules\sinon\lib\sinon.js:74:30)
      at Object.stub (C:\~censored~\node_modules\sinon\lib\sinon\stub.js:56:22)
      at Context.<anonymous> (C:\~censored~\test\myModelSpec.js:8:22)
      at Test.Runnable.run (C:\Users\~censored~\AppData\Roaming\npm\node_modules\mocha\lib\runnable.js:204:15)
      at Runner.runTest (C:\Users\~censored~\AppData\Roaming\npm\node_modules\mocha\lib\runner.js:374:10)
      at C:\Users\~censored~\AppData\Roaming\npm\node_modules\mocha\lib\runner.js:452:12
      at next (C:\Users\~censored~\AppData\Roaming\npm\node_modules\mocha\lib\runner.js:299:14)
      at C:\Users\~censored~\AppData\Roaming\npm\node_modules\mocha\lib\runner.js:309:7
      at next (C:\Users\~censored~\AppData\Roaming\npm\node_modules\mocha\lib\runner.js:247:23)
      at Object._onImmediate (C:\Users\~censored~\AppData\Roaming\npm\node_modules\mocha\lib\runner.js:276:5)
      at processImmediate [as _immediateCallback] (timers.js:330:15)